Stylus for recorders



Dec. 29, 1953 G. GORHAM 2,664,335

STYLUS FOR RECORDERS Filed Jan. 11, 1950 A INVENTOR.

' C760 e Gar/2cm: 36 ii I Q- CM' M Patented Dec. 29, 1953 STYLUS FORRECORDERS George Gotham, New York, N. Y., assignor to TechniconCardiograph Corporation, New York, N. Y., a corporation ApplicationJanuary 11, 1950, Serial No. 137,915

8 Claims. (Cl. 346-139) This invention relates to pens or styluses forrecording instruments, and more especially, though not exclusively, fordirect-writing electro-cardiographs.

It is the primary object of the present invention to provide a styluswhich is of such character that it has a substantially flat frequencyresponse, in that it responds uniformly to all frequencies within therange of frequencies of body voltages in the operation of theelectrocardiograph.

Another object of the present invention is the provision of a stylus ofthe above character, which is additionally characterized by itssimplicity of construction and its reliability in operation.

It is a yet further object of the present inven tion generally toprovide an improved stylus for electro-cardiographs or other recordinginstruments.

The above and other objects, features and advantages of the presentinvention will be more fully understood from the following descriptionconsidered in connection with the accompanying illustrative drawings.

In the drawings:

Fig. 1 is a top plan view of a stylus embodying the present invention;

Figs. 2 and 3 are side elevational and bottom plan views, respectively,of the stylus;

Fig. 4 is an enlarged section taken substantially on the line 4-4 ofFig. 1;

Fig. 5 illustrates perspectively the function of the instant stylus inan electro-cardiograph; and

Fig. 6 is an enlarged section taken on the line 6-6 of Fig. 1.

Referring to the drawings, and more particularly to Figs. 1 to 3thereof, the reference numeral l0 designates a recording pen or styluswhich comprises a blade 12 and a hub M on which the latter is mounted inheat-insulated fashion, To this end, the apertured end of the blade 12is received on a bushing I8 of any suitable heat-insulating material andrests on a preferably integral collar 16 on the latter (Fig. 4). Thebushing 18 is, in turn, received on the hub I4 and rests on a preferablyintegral end collar 32 of the latter. Received on the bushing 18 insuperposition on the apertured end 20 of the blade i2 is a spacer 22which preferably projects above the adjacent end of the bushing 18. Thespacer 22 may be made of the same insulating material as the bushing 18.Further received on the hub 14 is a collar 24 which is provided with aset screw 28. The hub l4 has a tapped hole 30 which is to receive theset screw 28 when the collar 24 is in position to hold the spacer 22,the bushing I8 and the interposed apertured end of the blade I 2securely against the end flange 32 of the hub M. In the presentinstance, a pin 34 is driven into the hub M, the bushing [8, theapertured end 20 of the blade l2, and the spacer 22, in order drivinglyto connect these parts. Thus, the blade I 2, which during theperformance of the instant stylus is heated in a manner and for apurpose hereinafter described, is eifectively heat-insulated from thepreferably metallic hub I4 and collar 24 by theinterposed bushing 48 andspacer 22. The hub 14 serves for mounting the stylus H] on anoscillatory operating spindle or shaft 36 of a record-- ing instrument,such as an electro-cardiograph. The stylus may conveniently be drivinglyconnected with the spindle 36 by the same set screw 28 which holds thecollar 24 on the hub M.

The blade [2 is preferably made from one of the metals classified in themetal arts as light metals, such as magnesium, aluminum, beryllium,copper and others. A presently preferred blade is made of a magnesiumalloy of the kind identifled by Dow Chemical Co. as FSl annealed, andconsisting of 95.7% magnesium, 3% aluminum, 1% zinc and 0.3% manganese.The blade [2 is at its recording end 38 preferably reduced widthwise toform a tip with which legibly to record an electro-cardiogram on a web Wof recording material (Fig. 5) in an electro-cardiograph of thedirect-writing type, for instance. Accordingly, the blade I2 is heatedso that its recording end or tip 38 will leave a visual record directlyon the recording web W. The web W may, to this end, be chemicallytreated paper of a known type on which the visual record is producedwhen being subjected to the heat of the contacting recording tip 38 ofthe stylus in the fashion shown in Fig. 5, while the web W is beingmoved longitudinally in the direction of the arrow A over the narrowedge 42 of a support or anvil 44 in a manner more fully disclosed in my00- pending applications Ser. No. 762,613, filed July 22, 1947, ser. No.788,801, filed November 29, 1947, now Pat. No. 2,524,564, issued October3, 1950, and Ser. No. 74,668, filed February 4, 1949. In order to heatthe recording end or tip 38 of the stylus, there is provided on theblade 12, and preferably wound directly on a portion of the recordingtip 38 itself, an electric heating coil 50 which has preferably integralleads 52 and 54 that extend rearwardly along the blade l2 to the spacer22 where they are connected with wires 56 and 58,

of an electro-cardiograph, for instance.

surface of certain paper, comparatively rapid wear of the recording tipof the stylus takes place, manifesting itself in ridges or;- grooves thetip of the stylus on the surface thereof next to the pointed edge of theanvil. or; platen 46, thus impairing the character ofthetrace formed onthe paper. To overcome this objection, the recording end or tip 38 oftheT instant: stylus. is, as best shown in Fig. 6, provided with awrapper 49 of any suitable chemically inertmaterial' which is notaffected by'the printing material with which the lines ontherecording-webare formed; A. satisfactory wrapper material for this.purpose is platinum foil, for instance. wrapper ill may conveniently beheld securely-on the recording stylus end 38 in any'suitable way as bythe heating. coil 5& which. is wound around the adjacent length. or theWrapper id. Of course, the wrapper flilzmay be dispensed-with if: theinstant stylus: is. used on. record material which does notadverselyafiect the stylus,

To further carryout the objective of a light weight. stylus, the.heating coil. 55 and its leads 52' and 54 are. preferably made from alength.

of light-gauge wire which is preferably glass coated for electricalinsulation, or otherwise coated with suitable insulation material whichsafely withstands the. heat emanating frcm'coil es. Wire known tothe-trade as Nichrome has been found suitable for said heating coil. Theleads 52 and 54. of: the heating coil 56- are pref.- erably passed fromone side-to theopposite-side of th blade i2 through holesfifiand 62therein,

respectively, and are electrically connected with thewires 5.6 and" 58in metal eyelets 64 and. 66, respectively, inwhich they are securedby-solders .o in any. other suitableway.

The eyelets. S42 and 66 are provided; in the spacer 22: (Fig. i) and?the. material from: which the. latter is madeis-preferably-alsoelectrically .insulating as isalsomember H6. Themetallic blade 12. is provided with furtherholes: 68 and it. in. orderto clear. themetallic eyelets 6& and

fifihrespectively; The blade l2.,.being made of minimum thickness. inaccordance with the ob- .jective of obtaining a stylus of'minimumweight,

is preferably reenforcedby an impressed longitudinal ridge or bead 74.

The instantstylus ifii is'characteristic for'its simple yet sturdyconstruction, and especially for its light weight which renders it souniformly responsive to all frequencies. within the range of frequenciesof body:voltages in the operation In-addition to the light weight of.the blade 52- itself, the fine Wllfl'Of theheating coil 50 andthe-rearward extension of the equally fine wire leads and 5'4. of thelatter to theeyeletsor terminals 65 and 66, respectively, further aid inre-.-

ducing. the weight of the instant stylusto a mini- .mum. The passagefof.the relatively-long leads and: 54: of the.- heatingcoil 58 througlr theholes es and (52, respectively, in theeblade l2:sub-

stantially midwaythereofeffectively prevents.

theseleads. from displacement sidewise; on the oscillating stylus.

The:

4 While I have shown and described the preferred embodiment of myinvention, it will be understood that various changes may be made in thepresent invention without departing from the underlying idea orprinciples or the invention witnm the scope of the appended claims.

Having thus described my invention, what I claim and es reto secure byLetters Patent is:

1. A stylus ifor making a record on heat-sensitive recording material,comprising a metallic blade having a recording end and an oppositeapertured; end, a metallic hub having a collar at one end, a sleeve ofheat-insulating material surrounding saldhub. and having an end collar iresting against said hub collar, said apertured blade end being-receivedby said sleeve and restagainst the collar of the latter, a spacer ofelectrical-and-heat insulating material received by said sleeve andoverlying said apertured blade end, a collar secured to said hub andengaging. said-spacer, to holdthe latter in firm. engagement. with a d"p rtures lade end;

a driving connecti n be ween. sai a r u s blade end and said hub, anelectricnheating coil electrically insula ingl e ur-m on, and 1 neaexchanee relation with, sa b ade nearh r cording. end thereof: spa l c.elets mounted in a d spacer. above: a ep rtu edblade end, ele ricai y.in ula d" eads 2ildmg from: th n s of. said; c l nt sa dy le iespectively, and current-supply wires ldading into said yelets. cspectve y. w ems Q I said e v and wires in a ye e re pec ively, b gns l tically c n ted-,vandsai blade e ng pr vided with aper ures. to ear; the;adiasent" e l t re:- spectively.

r c rd ng sty us a s t or h laim. 1, inzwhich aid le ds and ir n aid.- ets.- respectively) are ancho ed h latt r;- and. permanently heldelectrically connected by sol er in the; respective eyelets.

A 1 3 13491: mals nea record 011 heat-s nsitive reco d ng mater a omprin a m llic; b ade having a. c d ng end. and an opposite ap rtu d meansso iatedwith said l de adjacent said apertured end for nounting said ado s illati n n itsown ,p anas id mean including a member formed ofelectrical-andheat insulatingmaterial overlying said apertured bladeend,- an electricheating coil electrically nsula inelyn ed ndv n e tx harelation with, said blade near therecprding end thereof, spacedzmetalliceyelets'mountedin said member above saidapertured blade end,electrically insulatedleads extending from the ends of said coil intosaid eyelets, respectively; and current supply wires leading into saideyelets, respectively-the endsof; said leads and; wires in saideyelets,.respectively, being. electrically con.- nected, and said bladebeing providedwith apertures to. clear the adjacent eyelets,respectively.

A W S! a -dsfined'in fi. h ein said recording and is constituted byarecording tip formed by a. widthwisereduced. end length of the blade so;as to provide a shoulder between said tip and the remainder ofsaid-blade, and said coil-surrounds a length of said tipand bears aainst-- said; shoulder.

5. A stylus, as definedinclaim 4, wherein said tipisprovided with a.protective coat of heat. conductive, material which is chemically inertto,.the,.rec 0rding material.

.6 A1 stylus, as defined in claim 5, wherein said chemically inertprotective coat comprises a platinum foil wrapper onsaid tip.

7. A stylus for making a record on heat-sensitive recording material,comprising an elongated unitary metallic blad having a recording end andan opposite apertured end, means associated with said blade adjacentsaid apertured end for mounting said blade for oscillation in its ownplane, said means including a member formed of electrical-and-heatinsulating material overlying said apertured blade end, an electricheating coil electrically insulatingly mounted on, and

in heat-exchange relation with, said blade near the recording endthereof, electrically insulated leads extending from the ends of saidcoil, current-supply wires electrically connected to the ends of saidleads, respectively, and means to insulatingly secure said lead ends andsaid current supply wires to said blade adjacent said apertured bladeend, said recording end of the blade being formed by a widthwise reducedend length of the latter so as to provide a shoulder between said endlength and the remainder of said blade, and said coil surrounding aportion of said end length and bearing against said shoulder.

8. A stylus for making a record on heat-sensitary metallic blade havingan intermediate shank, a flat recording tip formed at one end of theshank by a widthwise reduced end length of the blade and a blademounting part formed at the other end of the shank to mount the bladefor oscillation in its own plane, an electric heating coil surroundingsaid tip and spaced inwardly from the free end of the tip, electricallyinsulated leads extending from the ends of said coil longitudinally ofsaid shank, and means to insulatingly secure said leads to said blademounting part, said tip having a shoulder and said coil bearing againstsaid shoulder.

GEORGE GORHAM.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 322,918 Farmer July 28, 1885 1,306,631 Rogers June 10, 19191,820,088 Parker et a1. Aug. 25, 1931 1,871,944 Best Aug. 16, 19321,901,921 Means Mar. 21, 1933 2,454,966 Faus Nov. 30, 1948 2,474,312Halpern June 28, 1949

